1. Field of the Invention
The invention relates to a personal audio listening device, more particularly to an earphone for use with a mobile communications device.
2. Description of the Related Art
Mobile phones having Bluetooth functionality and earphones having Bluetooth functionality have been popular for many years. R.O.C. Patent No. M257589 discloses a Bluetooth earphone as shown in FIGS. 1 and 2. The earphone 99 includes a stop plate 6, a housing 7, an ear hook member 8, and a pivotal knob 9. The housing 7 includes a first seat body 71 (adjacent to the user's face in use) and a second seat body (away from the user's face in use; not shown). The first seat body 71 is provided with a circular hole 713 therethrough. The housing 7 has a hollow portion 75 which accommodates a circuit board (not shown) therein for executing functions of a Bluetooth earphone. To facilitate description, the circuit board and the second seat body are neither illustrated in FIGS. 1 and 2 nor discussed in detail herein. The ear hook member 8 has a hook body 81 and a pivoting portion 83 disposed at one end. The hook body 81 is shaped to permit the ear hook member 8 to hook around an ear of the user. The pivoting portion 83 is cylindrical, and is provided with a plurality of axially extending planar faces 831 that are spaced equidistantly apart from each other on a peripheral surface of the pivoting portion 83. The pivotal knob 9 includes a base 91 and a cap 95. The base 91 has a bottom disk 911 and a post 913 extending uprightly from the bottom disk 911. The post 913 is formed with a first through hole 915 parallel to the bottom disk 911. An inner wall surface of the base 91 which defines the first through hole 915 is provided with a plurality of protruding members 917 that can be compressed resiliently and radially. The protruding members 917 correspond to the planar faces 831 of the pivoting portion 83 in number. The bottom disk 911 is provided with a first notch 92 and a second notch 93. The cap 95 is provided with a second through hole 955 corresponding to the first through hole 915. When the cap 95 is disposed on the post 913, the first and second through holes 915, 955 overlap. The stop plate 6 is a planar plate with pads 61 (to be described hereinafter) provided respectively at four corners thereof. The stop plate 6 has two parallel slots 63 formed therein so as to configure the stop plate 6 with a resilient cantilever arm 65. A block 651 is provided at a free end of the cantilever arm 65.
During assembly, the base 91 is extended through the circular hole 713 in the first seat body 71. At this time, the bottom disk 911 is blocked by the first seat body 71, and stays in the hollow portion 75. Then, the cap 95 is fitted on the post 913, with the pivoting portion 83 of the ear hook member 8 passing through the overlapping first and second through holes 915, 955, thereby coupling the ear hook member 8, the housing 7 and the pivotal knob 9. At this time, the stop plate 6 is attached to an inner surface (within the hollow portion 75) of the first seat body 71 using a mechanical fastening method or a chemical bonding method to cover the bottom disk 911. Since the four corners of the stop plate 6 are respectively provided with the pads 61 that have a certain thickness, although the stop plate 6 covers the bottom disk 911, it will not affect pivotal rotation of the pivotal knob 9. When the pivotal knob 9 rotates, the block 651 will interferingly engage one of the first and second notches 92, 93 to thereby achieve positioning. When the ear hook member 8 rotates in the through hole 915, positioning is achieved by means of inter-engagement between the radially compressible protruding members 917 and the planar faces 831 on the pivoting portion 83.
However, in the aforesaid patent, since the radially compressible protruding members 917 are provided on the inner wall surface of the base 91 which defines the first through hole 915, which is a relatively small hole, the construction of the base 91 is complicated. Besides, there is also the problem of difficulty in positioning between the protruding members 917 and the planar faces 831 on the pivoting portion 83. Moreover, in use, the pivoting portion 83 of the ear hook member 8 can be easily pulled out. In addition, manufacture and fastening of the stop plate 6 are labor- and time-consuming.